Climate expert predicts warmer-than-normal fall, continuing 10-year trend

Left, there’s a 55 percent chance of above-normal temperatures from August through October – a fairly strong likelihood, Thoman says. The 45 percent chance of above-normal temps throughout the rest of the state reflects a moderately-strong likelihood – the same chances of above-normal precipitation in southwestern and southeastern Alaska, right. (NOAA/National Weather Service)

National Weather Service climate expert Rick Thoman said there’s a good chance that all of Alaska will be warmer than normal in August and the next couple of months. But he said there’s near-certainty that coastal areas along the Gulf of Alaska and the Bering and Beaufort seas will be warm through October.

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Thoman said the computer models and array of sensors that he and other climate experts use to develop long-term forecasts suggest there’s a 45 percent chance that the eastern and central Interior will be warmer than normal through October. He said that’s a statewide trend that’s developed in recent years.

“The early Autumn season over most of the state, except for Southeast, in the last decade there’s been a really quite strong trend for a warm early Autumn season,” he said.

But Thoman said the models show an especially strong likelihood of warmer-than-normal temperatures in coastal areas through late summer and early fall. He said that’s mainly due to warm sea-surface temperatures and the absence of sea ice in the Bering and Beaufort seas.

The Arctic sea-ice extent around Alaska had by late last month receded more than the same time in 2016, which is tied with 2007 for the second-lowest minimum sea-ice extent on record.(NOAA/National Weather Service)

“Especially over northern and western Alaska – very low sea-ice cover,” Thoman said. “The ice cover left very early, even by modern standards, across the North Slope.”

Thoman said when Arctic sea ice cover retreats northward to its so-called minimum extent sometime in September, it probably won’t break the minimum-extent record set in 2012. But he said years of warming in the Arctic make it certain that it’ll be near the top of the list.

“It’s not a question of is it going to be above or below normal,” Thoman said. “The only real question is will it be the lowest? Will it be the second-lowest? Or will it be the third-lowest?

The Colorado-based National Snow and Ice Data Center reports Arctic sea-ice extent in early July appeared to be receding at a rate that rivaled the early July 2012 extent. But the rate of sea-ice decline slowed by mid-month, NSIDC says.

Thoman said precipitation is harder to predict a month out than it is for temperatures. But he said the models suggest near-normal precipitation throughout much of the state through October – except along the Bering Sea coast and Southeast Alaska, where higher-than-normal precipitation is likely.